1. Field of the Invention
This invention relates to connectors for elongate electrical heaters.
2. Introduction to the Invention
Elongate electrical heaters are well known and are used, for example, to prevent the freezing of pipes or to maintain process temperatures within pipes. Particularly useful elongate heaters comprise (a) first and second elongate electrodes, (b) a plurality of resistive heating elements connected in parallel between said electrodes, e.g. a continuous strip of a conductive polymer in which the electrodes are embedded or which is wrapped around the electrodes, and (c) an insulating jacket which surrounds the electrodes and the heating elements. It is often necessary to make an electrical connection from the elongate electrical heater, to another element, e.g. another heater or a power cord. Conventional methods of making such a connection by means of grommets, crimps, or heat-shrinkable sleeves have not satisfactoriy solved two problems which occur with such connections: adequate strain relief of the elongate heater and adequate sealing to prevent moisture, from such sources as condensation, from contacting the connection, e.g. after wicking down the heater. These problems are particularly serious when the elongate heater comprises a conductive metal braid which surrounds the insulating jacket and is for use in grounding the heater. Both the braid and the insulating polymer jacket must be adequately gripped in order to provide acceptable mechanical "pullout" strength, produce adequate strain relief, and prevent slipping of the insulating jacket with respect to the braid. In addition, the braid accelerates the wicking of moisture into the area of electrical connection. In order to provide an acceptable environmental seal, conventional connectors have utilized mastic, heat-shrinkable tubing, or resilient grommets. The resulting connector, which often must be prepared specifically for each size of heater and may comprise many components, may be bulky, requires craft-sensitive installation and cannot be easily reentered in order to modify the splice or check continuity of the connection and/or heater.